Jack Dorsey: 2 books that influenced me most have nothing to do with business

"Walk into a wealthy person's home and one of the first things you'll see is an extensive library of books they've used to educate themselves on how to become more successful," says self-made millionaire Steve Siebold in "How Rich People Think," which he wrote after studying millionaires for over 25 years.

1. "The Old Man and the Sea," by Ernest Hemingway

"I love the straightforwardness, the tightness and the poetry. I think it shows a common struggle that is repeated over and over in so many narratives both fictional and nonfictional."

2. "Leaves of Grass," by Walt Whitman

"I love the poets," Dorsey tells Y Combinator, including 19th-century American Walt Whitman, who published the first edition of "Leaves of Grass" in 1855.

"Poetry is kind of like programming —it's densifying very abstract concepts into a medium that allows interpretation. People can make the work their own and have better, more creative answers in life."

Plus, Whitman is "an interesting character" and "a total entrepreneur," adds the CEO.

"He self-published 35,000 copies of 'Leaves of Grass.' He was publishing it during the time of the Civil War and it's an edgy, questioning book. It questions racial equality, sexual equality, gender equality, all in one work."